Magnetic Force on Current
Fon current = I L B sin(qIB)
with direction: thumb(force) = hand(current) x fingers(field).
Example: If the earth has a magnetic field of 1 gauss directed North (for simplicity - it really is directed down and to the North), what is the magnetic force on a current of 100 amps flowing East in a wire 50 meters in length between two telephone poles.